Bacterial community composition under long-term reduced tillage and no till management.

AIMS: The purpose of this study was to assess impacts of long-term reduced tillage and no till management on bacterial communities in agricultural field soils. METHODS AND RESULTS: Samples from surface soils were collected from field plots maintained under reduced tillage and no till conditions for 14 years. No till soils had significantly higher microbial biomass, as well as ß-glucosidase activity, which is linked to organic matter breakdown. Sequencing of the 16S rRNA gene revealed most variability in bacterial community composition was observed in low abundance community members. Diversity estimates (Chao 1, ACE, and Shannon indices) were lower in no till soils, and several bacterial taxa linked to organic matter breakdown were significantly higher in no till compared to tilled soils. CONCLUSIONS: Long-term no till management can significantly enhance the size of soil microbial communities while negatively impacting bacterial diversity, through the lack of soil disturbance and breakdown of crop residues left on soil surfaces. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides insights into how no till management can influence the microbial community's contribution to soil health and suggests that long-term no till field plots may benefit from occasional tillage.